Air-compressor.



No. 700,927. 'Patented May' 27, I902.

E. HILL.

AIR COMPRESSOR (Application filed Aug. 17, 1901.) (No Model.) 4Sheets-Sheet 1!.

(No Model.)

PatentedMay 27, I902. E HILL.

AIR OQMPRESSOB.

(Applieatim med Aug. 17, 1901.)

4 ShaetsS heet 2,

No. 700,927. Patented May 27, I902.

E. HILL.

AIR COMPRESSOR.

(Application filed Aug. 17, 1901.)

4 Sheets-Sheet 3.

ZWMM.

No. 700,927. Patented May 27,1902.

-E. HILL.

AIR COMPRESSOR. (Application filed Aug. 17, 1901.)-

(NB Modem 4 Sheets-Sheet 4,

UNTTEE STATES PATENT OFFICE.

EBENEZER HILL, OF SOUTH NORWALK, CONNECTICUT.

AIR-COMPRESSOR.

SPECIFICATION forming part of Letters Patent No. 700,927, dated May 27,1902.

Application filed August 17, 1901. Serial No. 72,349. (No model.)

To (tZZ whom it may concern:

Be it known that I, EBENEZER HILL, a citizen of the United States,residing at South Norwalk, in the county of Fairfield and State ofConnecticut, have invented certain new and useful Improvements inAinCompressors, of which the following is a specification.

It is frequently necessary in factories to use compressed airattwodifferentpressures for example, it may be desired to draw air at twentypounds for cleaning castings and at the same time draw air at ninetypounds for running hoists and tools. Under ordinary conditions drawingair from between the cylinders of a compound compressor reduces thevolume of air to such an extent that the interpressure will not bemaintained.

This invention relates to a compound compressor so devised that air maybe drawn at two different pressures without material reduction ofpressure in the interreservoir.

The object is to so arrange the valves and connections of a compressorthat when air is drawn at low pressure from between the cylinders thesecond piston will automatically be rendered partly or whollyinoperative, thus leaving sufficient air between the cylinders tomaintain the pressure.

This invention resides in a compound aircompressor having a passageconnecting the interreservoir or other part of the duct between thecylinders and a specially-constructed inlet or discharge valve of thesecond cylinder, whereby on a reduction of pressure between thecylinders this special valve will be held open, so that the action ofthe second piston will be rendered ineffective and the volume of airwhich otherwise would be pumped forward by said piston will be re servedto prevent a reduction of volume and a consequent fall of pressure,which would otherwise be incident to the low-pressure demand.

Figure 1 of the accompanying drawings shows an elevation of a part of acompound air-compressor with the first and second cylinders in section.Fig. 2 shows a section of an ordinary inlet-valve. Fig. 3 shows asection of an ordinary discharge-valve. Fig. 4 shows a section of aspecial inlet-valve. Fig. 5 shows a section of a specialdischarge-valve. Fig. 6 is a diagram indicating the manner of using thespecial inlet-valve at each end to put the second cylinder entirely outof commission. Fig. 7 is a diagram indicating the use of a specialdischarge-valve at each end to put the second cylinder entirely out ofcommission. Fig. 8 is a diagram indicating the use of a specialinlet-valve at one end and a special discharge-valve at the other endfor putting the second cylinderoutof commission. Fig. 9 is a diagramindicating the use of a special inlet-valve and a special dischargevalveat the ends of the second cylinder opposite to the arrangementrepresented by Fig. 8. Fig. 10 is a diagram indicating the use of aspecial inlet-valve at one end for putting one half of the cylinder outof commission. Fig. 11 is a diagram indicating the use of a specialinlet valve for putting the other half of the second cylinder out ofcommission. Fig. 12 is a diagram indicating the use of a specialdischarge-valve at one end for putting that end of the cylinder out ofcommission.

Fig. 13 is a diagram indicating the use of a.

special discharge valve for putting the opposite half of the cylinderout of commission, and Fig. 14 is a view showing a modified means foroperating a discharge valve when the pressure in the cylinder-interductis reduced.

, The piston 1 in the double-acting first cylinder 2 of the compressorillustrated is connected with the piston 3 in the double-acting cylinder4 by a rod 5, which is adapted to be connected with steam-pistons intheusual manner. The first and second cylinders are connected by anordinary interreservoir 6, which may be any desired shape and diameterand which, with the openings to the valveports, forms the interduct. Thefirst cylinder ateach end has a common inlet-valve 7 and a commondischarge-valve 8. The second cylinder is shown with a commoninlet-valve 9 at one end and a common discharge-valve 10 at the otherend. If the inlet-valve at one end of the second cylinder is held open,that end of the cylinder will be inoperative. Holding thedischarge-valve at one end of the second putting an end of the cylinderout of commission is the pressure of air. It is possible to employgravity, as by means of a weight 44: and lever 45, instead of a springor air-pressure for this auxiliary force, as represented by dottedoutline in Fig. 14. These valves act automatically, and when one is heldopen the amount of air that would have passed through it and not returnis reserved to supply the place of that which is drawn 0E from theinterduct.

If it is desired to render the second cylinder entirely inoperative, oneof the above special inlet-valves could be usedat each end, as indicatedby Fig. 6, or one of the above-described discharge-valves could be usedat each end, as indicated by Fig. 7, or a special inlet-valve could beused at one end and a special discharge-valve could be used at the otherend of the second cylinder, as indicated by Figs. 8 and 9. If it isdesired to put only one half of the second cylinder out of commission,one special inlet or one special discharge valve can be used at eitherend, as indicated by Figs. 10, ll, 12, and 13.

By means of the simple mechanism described it is possible to furnish airat high and low pressures with a single compressor so as to meet theordinary demands of a factory.

I claim as my invention- 1. A compound air-compressor having cylinders,pistons, inlet and discharge valves and cylinder-interduct, means foropening a valve of the second cylinder, and a passage so connecting saidinterduct with the valveopening means that the pressure in thecylinder-interduct controls the operation of the valve-opening means,substantially as specified.

2. A compound air-compressor having cylinders, pistons, inlet anddischarge valves and cylinder-interduct,means tending to open aninlet-valve of the second cylinder, a passage-so connecting saidinterduct with the chamber of said inlet-valve that the normal pressurein the cylinder-interduct is exerted oppositely to and holds in checkthe means tending to open said inlet-valve, substantially as specified.

3. In a compound air-compressor having cylinders,'pistons, inlet anddischarge valves and cylinder-interduct, a valve-piston, means formoving the valve-piston so it will open a valve of the second cylinder,and a passage so connecting said interduct with the valvepiston chamberthat the normal pressure in the cylinder-interduct is exerted oppositelyto and holds the means for moving the valvepiston, substantially asspecified.

4. A compound air-compressor having cylinders, pistons, inlet anddischarge valves and cylinder interduct, a valve-piston, a spring formoving the valve-piston so it will open a valve of the second cylinder,and a passage so connecting said interduct with the valve-piston chamberthat the normal pressure in the cylinder-interduct is exerted oppositelyto and holds the means for moving the valve-piston, substantially asspecified.

5. A compound air-compressor having cylinders, pistons, inlet anddischarge. valves and cylinderinterduct, a valve-piston, a spring formoving the valve-piston into contact with a portion of a valve of thesecond cylinder, and a passage so connecting said interduct with thevalve-piston chamber that the normal pressure in the cylinder-interductis exerted oppositely to and overcomes the spring, substantially asspecified.

EBENEZER HILL.

Witnesses:

E. HILL, J r., J. E. SLATER.

